Harmonic neutralizing amplifier



Feb. 27, 1934. T. H. NAKKEN 1,949,217

mnmomc NEUTRALIZING AMPLIFIER Filed June 12. 1929 INVENTOR 1.15 H.MRI/(KEN ATTORNEY Patented Feb. 27, 1934 STATES Theodorus H. Nakken,Brooklyn, N. Y., assignor to Nakken Patents Corporation, a corporationof Delaware Application June 12, 1929. Serial No. 370,296

2 Claims.

This invention relates to amplifiers for feeble periodic signalvariations such as the electric variations from phonograph pickup,sound-onfilin pickup, radio receiver and the like.

The object of the invention is to effect large amplification in anefficient manner by means of simple apparatus and with a minimizing ofamplitude distortion.

In carrying out the general object of the invention I possible theutilization of direct cascade coupling between triode amplifiers bycombining two similar series of triode amplifiers connected with anelectromagnetic differential mechanism at the out at end and with meansfor dividing the initial signal impulse between said two series at theinput ends thereof.

The above and further objects of the invention will be pointed out morein detail in the following claims which are directed to an illustrativeembodiment of the invention described in the following specification inconnection with the accompanying drawing solely for purposes ofi1lustration and not limitation.

In the drawing, the single figure is a diagram illustrating myinvention.

I combine two series of triode amplifiers, one the series A, A1 and A2and the other the series A, Ai and Az. The last triodes of the series A2and A2 are preferably of the power type capable of delivering a largeplate current. All of the triodes are shown of the heater cathode type.It is an essential of the invention that the cathodes of all of thetriodes of the series, except those of the last stage, have potentialfloating cathodes. This is a quality of triodes in which the cathode isexcited by heat from an independent disconnected heater. Although I haveshown the triodes of the last stage of the two series of the samecharacter, it is not essential to the invention that the cathodes of thetriodes A2 and Az be potential floating as they are both conductivelyconnected by lead 1 to the negative terminal 2 or" a suitable source ofdirect current potential 3. An important element in my invention is anelectromagnetic diiierential device 4 shown in the form of a transformerhaving a primary coil made up of two similar parts 5 and 6 with a centertap 7 leading to the positive terminal of the source 3. A singlesecondary 8 is magnetically linked with the coils 5 and 6 and isresponsive to the differential effect of these two coils, the terminalsof which are respectively connected by conductors 9 and 10 with theplates P of all the triodes of each series of triode amplifiers.

The grid of the last triode of each series is connected by a conductiveconnection with the cathode of the next preceding triode. Connections 11and 12 serve this purpose between triodes A1 and A2 and A1 and A'zrespectively, while conductors 13 and 14 serve the same purpose for thetriodes A and A1 and A and A'1 respectively.

An input coil 15 is shown directly connected at its terminals to thegrid G and the cathode C of the first triode A of one series and asecond similar input coil 16 is symmetrically connected to the grid andthe cathode of triode A. The periodic electric signal to be amplified isled to a primary coil 17 which is magnetically linked to the coils 15and 16 as by core 18. Care should be taken in the winding of coils 15and 16 to minimize mutual coupling therebetween, both capacity couplingand magnetic coupling, so that the virtual potential or electrostaticpotential of each of the coils l5 and 16 may float as freely as possiblerelatively to each other. The direction of the winding of thecoils 15and 16 is such that coil 15 tends to make grid G of triode A morepositive relatively to its cathode C and the coil 16 tends to make gridG of triode A more negative relatively to its cathode C and vice versa.

Operation For condition of no signal reception and with all cathodesexcited into condition of electron emission, a condition of differentialbalance between the two combined plate circuits of the two series ispresent. One circuit traced in the direction of electron flow is fromnegative lead 2 to the cathodes C of A2 and A'z. Thence, placing thepath through one series, a part of the electron stream flows to plate Pof triode A2 and thence through coil 5 to the positive terminal of thesource, but a part flows to the positive grid G of this triode overconductor 11 to the cathode of triode A1 and thence branches part to itsplate P back to the positive terminal of the source through coil 5 andpart to the positive grid G of triode A1 over conductor 13 to cathode Cof triode A, thence to the plate of triode A and back through coil 5 tothe positive terminal of the source. A similar symmetrical circuit withsimilar and symmetrical branches may be traced in an obvious manner forthe triode series A, Ai, Az which is, ,of course, limited to the coil 6.Thus for this condition, the magnetizing effect of the two platecircuits differentially combined is zero.

When the coil 15 is tending to make grid G of triode A more positive andcoil 16 is tending to make grid G of triode A more negative bothrelatively to their respective cathodes, the following changed conditiontakes place. The controlling efiect of grid G of triode A causes anincrease in the fiow of electrons to the plate of this triode from itscathode C. The only source for these electrons is the grid G of thesucceeding triode A1. The efiect of drawing electrons from this grid isto make it electrostatically more positive or less negative which inturn effects an increase of electron flow from its cathode C to itsplate P. The only source from which cathode C of triode A1 can drawelectrons is the grid G of the last triode A2 of the series which,becoming more positive, increases the electron fiow fromits cathode C toits plate P. Thus there is an increased electron flow or an increasingelectron fiow through coil 5. In a similar manner for the series A, A'l,Az, the more negative or less positive condition for grid G of triode Aeffects an opposite condition for this series of triode. Electrons at alower rate fiow from cathode C to plate P of triode A. Electrons aredrawn out of grid G of triode A'i at a lower rate with the effect thatthis grid becomes more negative and from its controlling eifect upon theelectron stream, reduces the rate of electron flow from its cathode toits plate. Likewise the cathode C of triode Ai draws electrons at alower rate over conductor 12 from grid G of triode A'z to effect by itscontrol a lessening of the rate of electron fiow from its cathode to itsplate. Therefore, a tendency to decrease for the current through thecoil 6 takes place. The electromagnetic linkage between coils 5, 6 and 8imparts to coil 8 the combination of the increase of flow through coil 5and the decrease in flow through coil 6. For the next half of the waveof the periodic disturbance in coil 17, the reverse of this functioningtakes place but in both cases there is imparted to the output coil 8 ahalf wave of similar form regardless of any dissimilarity in formbetween the simultaneous variations of periodic energy variation incoils 5 and 6.

What I claim and desire to secure by United States Letters Patent is:

1. A full wave amplifier assemblage for amplifying periodic signalvariations comprising two symmetrical series of three or more directconnected triode amplifiers; a separate input coil for each said seriesand operatively connected to the grid and the cathode of the firsttriode amplifier of said series; an electromagnetic differential coilresponsive to both said series; and a single source of plate circuitpotential connected between the midpoint of said electromagneticdiiferential coil and the two cathodes of the last triode amplifiers ofsaid two symmetrical series.

2. An amplifier assemblage for minimizing amplitude distortioncomprising two triode amplifier series, each comprising an equal numberplurality of triode amplifiers, the electrodes of all said triodeamplifiers except the cathodes of the last triodes of the series beingfree from conductive and capacity coupling with relation to the rest ofsaid system and therefore free to float in potential in response tosignal control; an input coil for each series having terminal connectionwith the grid and the cathode of the first triode of said series; acathode of each triode having a conductive connection with the grid ofthe succeeding triode of said series; an electromagnetic plate circuitdifferential means; a conductive connection connecting all the plates ofeach series respectively to said differential means, a source of directcurrent potential; and connections connecting said source with thecathodes of the last triode of said two series and with saiddifferential device.

THEODORUS H. NAKKEN.

